The present device pertains generally to swivels and more particularly to a swivel capable of withstanding high impact forces while providing a hermetical seal.
In the design of electronic equipment, it is often necessary to provide a hermetically sealed unit in which the electronic equipment can be stored. Atmospheric pressure and desired humidity can be sealed in the electronic unit to prevent problems such as breakdown and corona buildup that occurs with the low pressures that are associated with the high altitudes at which the device is used. In addition, a hermetically sealed unit is often needed to encapsulate a cooling liquid necessary in the device to create a steady state temperature condition, preventing instability and, in many cases, thermo-runaway. Also, a hermetically sealed unit is desirable since the shelf life of the unit can be extended by preventing the day-to-day changes in atomospheric pressure and humidity which affect hydroscopic changes in the battery cells stored within the unit. Finally, a hermetically sealed unit allows the jamming device to float to aid in recovery of the unit thereby allowing the device to be reused numerous times to reduce the system's overall cost.
It is therefore desirable to provide a means for attaching a parachute to the device in a manner which allows the unit to be hermetically sealed. Standard attachment rings affixed in a stationary manner to the unit have caused the parachute riser and shroud lines to become twisted or entangled due to the rotation of the device. Conventional swivel devices which have been used to attach the parachute to the unit have not provided the necessary hermetical seal required by the unit and, in addition, have not been able to withstand the forces created upon the opening of the parachute. Swivels which can withstand these initial opening forces have provided neither the hermetical seal nor the low friction rotational freedom required to prevent entanglement of the parachute during descent.